Fluid-filled vibroisolating device

ABSTRACT

A fluid-filled vibroisolating device comprises a joint member adapted to be joined to a vibrating body such as an engine. A support member is adapted to be supported on a supporting body such as a vehicle frame and defining an expandable and contractible auxiliary fluid chamber filled with a fluid. An elastomeric member interconnects the joint and support members and is disposed in a vibrating direction in which the vibrating body vibrates. The elastomeric member, the joint member, and the support member jointly define an expandable and contractible main fluid chamber filled with a fluid. A partition is mounted in the support member and separates the main and auxiliary fluid chambers from each other. The partition has flow regulators for regulating the flow of the fluid between the main and auxiliary fluid chamber. A reinforcing member is integrally formed with the elastomeric member for preventing the elastomeric member from being collapsed. By selecting various parameters of the device to meet a predetermined equation, and providing as the flow regulating mechanism an orifice between the main and auxiliary fluid chambers for allowing the fluid to flow or resonate, and also a movable plate movable dependent on the difference between the fluid pressures in the main and auxiliary fluid chambers, the damping capability of the fluid-filled vibroisolating device is improved and the dynamic spring constant thereof is uniformly lowered in a wide range of frequencies.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a fluid-filled vibroisolating devicehaving an expandable and contractable fluid chamber made of anelastomeric material or the like and filled with a fluid, and moreparticularly to a fluid-filled vibroisolating device for use as avibroisolating or vibration damping support for a power unit such as anautomotive engine or the like.

2. Description of the Relevant Art:

Motor vehicles such as automobiles develop various vibrations ofdifferent frequencies and amplitudes dependent on operating conditionssuch as engine rotational speeds, varying road surfaces, and the like.Therefore, the motor vehicles are required to be equipped withvibroisolating or vibration damping devices capable of absorbing ordamping vibrations in a wide range of frequencies and amplitudes.

Known vibroisolating devices include a fluid-filled vibroisolatingdevice comprising a support member on which a vibrating body such as anengine is mounted, a support member installed on a support body such asa vehicle frame, and an elastomeric body of rubber, for example, havingopposite ends fixed to the support members and defining a main fluidchamber therein. The fluid-filled vibroisolating device also includes anauxiliary fluid chamber communicating with the main fluid chamberthrough an orifice. The main and auxiliary fluid chambers are filledwith a noncompressible fluid such as water, oil, or the like.

The main and auxiliary fluid chambers are divided by a partition whichhas the orifice providing fluid communication between the main andauxiliary fluid chambers. Vibration of the engine is generally absorbedand/or dampened by elastic deformation of the elastomeric body and theflow of the fluid through the orifice between the main and auxiliaryfluid chambers.

There has been a demand for improved dynamic spring characteristics andimproved damping capability for such fluid-filled vibroisolatingdevices. Japanese Laid-Open Patent Publication No. 60-263736 discloses afluid-filled mount as one example of the fluid-filled vibroisolatingdevice. The publication discloses that by causing the fluid flowingthrough the orifice to resonate, a loss coefficient, i.e., a dampingcoefficient at a desired frequency of vibration can be increased and adynamic spring coefficient can be reduced.

Though the disclosed fluid-filled mount somewhat improves its dynamicspring characteristics and damping characteristics, it is desired thatthese characteristics should be more improved.

More specifically, the elastomeric body of the mount which substantiallydefines the main fluid chamber is low in rigidity in a direction(hereinafter referred to as an expanding direction) normal to thedirection of vibration, and tends to collapse when the exciting forcefor developing the vibration is large. To eliminate this drawback, therehas been proposed in recent years a mount including an intermediatereinforcing member which reinforces an elastomeric body to increase itsrigidity. In the proposed mount, the elastomeric body which defines amain fluid chamber is divided into two elastomeric members which arejoined to each other by the intermediate reinforcing member for therebyincreasing the rigidity of the entire elastomeric body in the expandingdirection to guard against collapsing under strong vibration. Since,however, the intermediate reinforcing member which has a relativelylarge mass is positioned between the vibrating elastomeric members,these members constitute a vibratory system causing the intermediatereinforcing member to vibrate. As shown in FIG. 8, the vibration of theintermediate reinforcing member is liable to give rise to peaks of thedynamic spring constant of the entire system at medium and highfrequencies, with the result that the transmission of vibration incertain frequency ranges, particularly medium and high frequency ranges,to the vehicle frame cannot effectively be reduced. To minimize adverseeffects resulting from the use of the intermediate reinforcing member,the shape and weight of the intermediate reinforcing member have to bestrictly designed, and the range of shapes and weights thereof that areavailable is considerably limited.

The orifice may be formed in various shapes in order to cause the fluidflowing therethrough to flow desirably or resonate at appropriatetiming. An orifice shape has been desired which can achieve a uniformreduction in the dynamic spring constant in a wide range of frequencies,particularly a high frequency range.

In view of the problems of the conventional fluid-filled vibroisolatingdevice, it is an object of the present invention to provide afluid-filled vibroisolating device which has an improved dampingcapability and can reduce the dynamic spring constant uniformly in awide range of frequencies.

According to the present invention, there is provided a fluid-filledvibroisolating device comprising a joint member adapted to be joined toa vibrating body such as an engine, a support member adapted to besupported on a supporting body such as a vehicle frame and defining anexpandable and contractable auxiliary fluid chamber filled with a fluid,an elastomeric member interconnecting the joint and support members anddisposed in a vibrating direction in which the vibrating body vibrates,the elastomeric member, the joint member, and the support member jointlydefining an expandable and contractable main fluid chamber filled with afluid, a partition mounted in the support member and separating the mainand auxiliary fluid chambers from each other, the partition having flowregulating means for regulating the flow of the fluid between the mainand auxiliary fluid chambers, and a reinforcing member integrally formedwith the elastomeric member for preventing the elastomeric member frombeing collapsed. Various parameters of the fluid-filled vibroisolatingdevice are selected to approximately meet the equation: ##EQU1## whereSE is the effective fluid draining area which contributes to a change inthe volume of the main fluid chamber when the joint member is displacedwith the support member fixed, Si is the effective fluid draining areawhich contributes to a change in the volume of the main fluid chamberwhen the reinforcing member is displaced in the vibrating direction withthe joint and support members fixed, k1 is the static spring constantwhen the joint member is displaced in the vibrating direction with themain fluid chamber open and the reinforcing member fixed, k is thestatic spring constant when the joint and support members are relativelydisplaced in the vibrating direction with the main fluid chamber open,and K is the static spring constant when the joint and support membersare relatively displaced in the vibrating direction with the flowregulating means closed.

With this construction, the reinforcing member is prevented from beingvibrated, and the dynamic spring characteristics of the entire device isnot affected by the reinforcing member. The dynamic spring constant ofthe device is uniformly lowered in a full range of vibration frequenciesfor thereby reducing vibration transmitted.

The partition has a storage chamber defined therein and held incommunication with the main and auxiliary fluid chambers through aplurality of first orifices opening into the main fluid chamber and aplurality of second orifices opening into the auxiliary fluid chamber incoaxial relation to the first orifices as pairs. The flow regulatingmeans comprises a movable plate movably disposed in the storage chamberand movable at least axially of the first and second orifices dependenton the difference between fluid pressures in the main and auxiliaryfluid chambers, the first and second orifices having openings openingtoward the movable plate, the openings of at least one of the first andsecond orifices having tapered portions flaring toward the movableplate.

When vibration of a small amplitude is applied to the device, themovable plate is moved to absorb a change in the fluid pressure, and theelastomeric member is prevented from resonating through resonant actiondue to the mass of the fluid in the orifices and a spring component ofthe elastomeric member relative to the fluid pressure, so that thedynamic spring characteristics can be prevented from being lowered. Themovable plate in the storage chamber has a small area of contact withother members, for effectively contributing to the absorption of changesin the fluid pressure and the prevention of resonance of the elastomericmember. When vibration with a large amplitude is applied, the movableplate is not moved, but the fluid pressure is increased for highervibration damping capability.

The partition comprises an upper plate comprising a base plate in theform of a thin metallic sheet and an elastomeric body bonded thereto,and a lower plate in the form of a thin metallic sheet. Therefore,orifices of complex shape can be defined in the partition, and any burrson the partition can easily be removed.

The above and further objects, details and advantages of the presentinvention will become apparent from the following detailed descriptionof preferred embodiments thereof, when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a fluid-filled vibroisolating deviceaccording to a first embodiment of the present invention;

FIG. 2 is a diagram showing a vibration model of the fluid-filledvibroisolating device shown in FIG. 1;

FIG. 3 is a view showing an arrangement for measuring an effective fluiddraining area SE in the fluid-filled vibroisolating device shown in FIG.1;

FIG. 4 is a view showing an arrangement for measuring an effective fluiddraining area Si in the fluid-filled vibroisolating device shown in FIG.1;

FIG. 5 is a view showing an arrangement for measuring static springconstants k, k1, K in the fluid-filled vibroisolating device shown inFIG. 1;

FIG. 6 is a cross-sectional view of a modification of the fluid-filledvibroisolating device shown in FIG. 1;

FIG. 7 is a diagram of the characteristic curve of a dynamic springconstant of the fluid-filled vibroisolating device shown in FIG. 1;

FIG. 8 is a diagram of the characteristic curve of a dynamic springconstant of a conventional fluid-filled vibroisolating device;

FIG. 9 is a cross-sectional view of a fluid-filled vibroisolating deviceaccording to a second embodiment of the present invention;

FIG. 10 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a first modification of the second embodiment shownin FIG. 9;

FIG. 11 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a second modification of the second embodiment;

FIG. 12 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a third modificationof the second embodiment;

FIG. 13 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a fourth modification of the second embodiment;

FIG. 14 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a fifth modification of the second embodiment;

FIG. 15 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a sixth modification of the second embodiment;

FIG. 16 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a seventh modification of the second embodiment;

FIG. 17 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to an eighth modification of the second embodiment;

FIG. 18 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a ninth modification of the second embodiment;

FIG. 19 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a tenth modification of the second embodiment;

FIG. 20 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to an eleventh modification of the second embodiment;

FIG. 21 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a twelfth modification of the second embodiment;

FIG. 22 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a thirteenth modification of the second embodiment;

FIG. 23 is a diagram of a dynamic spring constant characteristic curveobtained when an orifice diameter is smaller or an effective length isgreater in the fluid-filled vibroisolating device according to secondembodiment shown in FIG. 9;

FIG. 24 is a diagram of a dynamic spring constant characteristic curveobtained when an orifice diameter is greater or an effective length issmaller in the fluid-filled vibroisolating device according to secondembodiment shown in FIG. 9;

FIG. 25 is a cross-sectional view of a fluid-filled vibroisolatingdevice shown as a comparative example with respect to the secondembodiment of FIG. 9;

FIG. 26 is a cross-sectional view of a fluid-filled vibroisolatingdevice according to a third embodiment of the present invention;

FIG. 27 is an enlarged vertical cross-sectional view of a partitionemployed in the fluid-filled vibroisolating device according to thethird embodiment;

FIG. 28 is a plan view of the partition illustrated in FIG. 27; and

FIG. 29 is a vertical cross-sectional view of a partition according to amodification of the partition shown in FIG. 27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 through 7 show a fluid-filled vibroisolating device according toa first embodiment of the present invention.

The fluid-filled vibroisolating device according to the first embodimentwill hereinafter be described as being employed for supporting a powerunit such as an automotive engine.

As shown in FIG. 1, the fluid-filled vibroisolating device includes asubstantially column-shaped joint member 111 to be attached to the powerunit, a substantially tubular support member to be mounted on a vehicleframe, and an elastomeric member 113 made of an elastomeric materialsuch a rubber interposed between and joined to the members 111, 113. Thejoint member 111 has a threaded hole 111a and is coupled to the powerunit by a bolt threaded into the hole 111a. Likewise, the support member112 has attachment holes 112a and is fastened to the vehicle frame bybolts inserted through the attachment holes 112a. In the illustratedembodiment, the elastomeric member 113 is divided into two elastomericbodies 113a, 113b joined to each other by an intermediate reinforcingmember 114 of a highly rigid material such as metal. However, theelastomeric member 113 may be constructed otherwise. The elastomericbody 113ahas an upper end (as shown) fixed to the joint member 111, andthe elastomeric body 113b has a lower end (as shown) fixed to thesupport member 112. The intermediate reinforcing member 114 makes theelastomeric member 113 highly rigid in an expanding direction which is ahorizontal direction in FIG. 1.

To the support member 112, there is affixed an elastically deformablediaphragm 115 of an elastomeric material such as rubber or the like at alower inner peripheral surface of the support member 112. The supportmember 112 has a partition member 116 therein which has a flow passage117 in the form of an orifice in the illustrated embodiment locatedabove the diaphragm 115, the flow passage 117 serving as a means forregulating the flow of a fluid therethrough.

The members 111, 112, the elastomeric member 113, and the partition 116jointly define an expandable and contractable main fluid member 118filled with a fluid such as oil or the like. The support member 112, thediaphragm 115, and the partition member 116 jointly define an expandableand contractable auxiliary fluid chamber 119 filled with a fluid such asoil or the like. The main and auxiliary fluid chambers 118, 119 are heldin fluid communication with each other through the flow passage 117defined through the partition member 116.

The fluid-filled vibroisolating device of the first embodiment hasvarious parameters which are selected appropriately as described lateron, such that when the members 111, 112 are relatively displacedvertically by the vibration of the power unit or the vehicle frame, theelastomeric bodies 113a, 113b are elastically deformed as indicated bythe two-dot-and-dash lines in FIG. 1, without causing vibration of theintermediate reinforcing member 114. When vibration is applied with alarge amplitude at a low frequency, the elastomeric bodies 113a, 113bare largely deformed to cause the main fluid chamber 118 to changelargely in its volume. The fluid is forced to flow through the flowpassage 117 between the main and auxiliary fluid chambers 118, 119 forthereby dampening the vibration. It is also possible to uniformly reducea dynamic spring constant with respect to vibration with a smallamplitude at a high frequency, so that the transmission to the vehiclebody of secondary vibration of the engine or the like which tends toproduce confined sound in the automobile cabin can effectively bereduced.

More specifically, it is assumed that an effective fluid draining areawhich contributes to a change in the volume of the main fluid chamber118 when the joint member 111 is vertically displaced (in the vibratingdirection) with the support member 112 fixed is indicated by SE, aneffective fluid draining area which contributes to a change in thevolume of the main fluid chamber 118 when the intermediate reinforcingmember 114 is displaced in the vibrating direction with the members 111,112 fixed is indicated by Si, a static spring constant when the jointmember 111 is displaced in the vibrating direction with the flow passage117 open and the intermediate reinforcing member 114 fixed is indicatedby k1, a static spring constant when the members 111, 112 are relativelydisplaced in the vibrating direction with the flow passage 117 open isindicated by k, and a static spring constant when the members 111, 112are relatively displaced in the vibrating direction with the flowpassage 117 closed is indicated by K. These areas SE, Si, and the staticspring constants k1, k, K are selected to approximately meet thefollowing equation (1): ##EQU2##

The fluid-filled vibroisolating device thus constructed is representedby a vibration model shown in FIG. 2. When the joint member 111 isdisplaced downwardly by χ in response to vibration of the power unit, apressure P indicated by the equation (2) below is developed in the mainfluid chamber 118. The pressure P serve to produce a force Fp indicatedby the equation (3) below, the force Fp tending to push the intermediatereinforcing member 114 upwardly. The resiliency of the elastomeric body113a produces a force Fk indicated by the equation (4) below, tending topush the intermediate reinforcing member 114 downwardly. ##EQU3## where##EQU4## The aforesaid embodiment fulfills the equation (1), and usinga, the equation (1) can be expressed as follows: ##EQU5## By putting theequation (1') into the equation (3), the force Fp is equalized to theforce Fk indicated by the equation (4). Thus, the forces Fp, Fk actingon the intermediate reinforcing member 114 are kept in equilibrium, sothat the intermediate reinforcing member 114 is not vibrated. Therefore,the characteristics of fluid-filled vibroisolating device such as thedynamic spring constant are not affected by the intermediate reinforcingmember 114. The dynamic spring constant has a characteristic curve asshown in FIG. 7 for effectively reducing vibration which is transmittedto the vehicle body.

Measurement of the effective fluid draining areas SE, Si will bedescribed with reference to FIGS. 3 and 4, and measurement of the staticspring constants k, k1, K will be described with reference to FIG. 5.

First, measurement of the effective fluid draining area SE will bedescribed. As shown in FIG. 3, the effective fluid draining area SE isdetermined by applying a displacement χE to the joint member 111 withthe support member 112 fixed, introducing the fluid discharged from themain fluid chamber 118 by the displacement χE of the joint member 111through a nipple 120 and a hose 121 into a measuring container 122 andmeasuring the amount of the discharged fluid, and dividing the measuredamount VE of the fluid by the displacement χE of the joint member 111 asindicated by the following equation (5): ##EQU6##

Likewise, as shown in FIG. 4, the effective fluid draining area Si isdetermined by applying a displacement χi to the intermediate reinforcingmember 114 with the members 111, 112 fixed, and dividing the amount Viof the fluid discharged from the main fluid chamber 118 at this time bythe displacement χi of the intermediate reinforcing member 114(according to Vi/χi).

As illustrated in FIG. 5, the static spring constant k1 is determined byopening the main fluid chamber 118 and fixing the intermediatereinforcing member 114, measuring a displacement χ1 produced when thejoint member 111 is pushed downwardly under a force F1, and dividing theforce F1 by the displacement χ1 as indicated by the following equation(6): ##EQU7##

Similarly, the static spring constant k is determined by opening themain fluid chamber 118, measuring a relative displacement χ producedwhen the members 111, 112 are pushed vertically under a force F, anddividing the force F by the displacement χ . Likewise, the static springconstant K is determined by closing the flow passage 117 as with a plug,measuring a relative displacement χo produced when the members 111, 112are pushed vertically under a force Fo, and dividing the force Fo by therelative displacement χo.

A fluid-filled vibroisolating device according to a modification of thefirst embodiment will be described with reference to FIG. 6.

Those parts in FIG. 6 which are identical to those of the firstembodiment are denoted by identical reference numerals and will not bedescribed in detail.

The partition member 116 has, in addition to the flow passage 117, astorage chamber 123 defined therein and held in communication with themain and auxiliary fluid chambers 118, 119 through a plurality oforifices 123a, 123b . A floating plate 124 is floatingly stored in thestorage chamber 123, the floating plate 124 being capable of closing theorifices 123a or the orifices 123b at a time. The flow passage 117 isdefined in an outer peripheral edge of the partition member 116.

When vibration is applied with a small amplitude at a high frequency(higher than about 200 through 300 [Hz]) to the fluid-filledvibroisolating device, the fluid flows between the main and auxiliaryfluid chambers 118, 119 through the orifices 123a, 123b and the storagechamber 123, and also through the flow passage 117. Under vibration witha large amplitude at a low frequency, the floating plate 124 closes theorifices 123a or the orifices 123b, allowing the fluid to flow onlythrough the flow passage 117 between the main and auxiliary fluidchambers 118, 119. Therefore, as with the fluid-filled vibroisolatingdevice of the first embodiment, the fluid-filled vibroisolating deviceshown in FIG. 6 can effectively dampen the vibration with a largeamplitude at a low frequency, and can reduce the dynamic spring constantwith respect to the vibration with a small amplitude at a highfrequency, so that the transmission of vibration to the vehicle body canbe lowered.

The effective fluid draining areas SE, Si and the static springconstants k1, k, K of the fluid-filled vibroisolating device of FIG. 6also fulfill the equation (1) above. Consequently, the intermediatereinforcing member 114 is prevented from vibrating particularly in a lowfrequency range in which the orifices 123a or the orifices 123b areclosed by the floating plate 124, so that the dynamic spring constantcharacteristics as shown in FIG. 7 can be obtained.

As described above, with the fluid-filled vibroisolating devices of thefirst embodiment and its modification, the dynamic spring constant canbe reduced in a wide range of frequencies according to a flatcharacteristic curve while increasing the rigidity of the elastomericbodies in the expanding direction, and the transmission of vibration caneffectively be lowered.

Fluid-filled vibroisolating devices according to a second embodiment andits modifications will now be described with reference to FIGS. 9through 25. FIG. 9 shows a fluid-filled vibroisolating device of asecond embodiment which comprises a joint member 201a to be attached toa vibrating body, an annular support member 202ato be mounted on asupport body on which the vibrating body is to be installed, and anannular elastomeric member 204a reinforced with an annular reinforcingmember 203 and interconnecting the joint member 201a and the supportmember 202a. The support member 202a has an annular barrel having anattachment flange on one of its vertical ends. The elastomeric member204a is fixed to the support member 202a along the end near theattachment flange. A diaphragm 205 has an outer peripheral edge joinedto the inner peripheral surface of the other end of the barrel of thesupport member 202a. The elastomeric member 204a, the support member202a, and the diaphragm 205 jointly define a fluid chamber filled with anoncompressible fluid. A partition 206 a is disposed in the fluidchamber and has its outer peripheral edge fixed to the inner peripheralsurface of the barrel of the support member 202a. The partition 206adivides the fluid chamber into an expandable and contractable firstfluid chamber 207 adjoining to the elastomeric member 204a, and anexpandable and contractable second fluid chamber 208 adjoining to thediaphragm 205. The partition 206a has a number of orifices 209a definedtherein and extending from the first fluid chamber 207 to the secondfluid chamber 208. A movable plate 210a is disposed in the partition206a across the orifices 209a and movable or vibratable in the orifices209a dependent on a change in the pressure of the fluid. Each of theorifices 209a has a flaring or tapered portion 211 near the first fluidchamber 207 and flaring toward the movable plate 210a.

More specifically, as shown in FIG. 9, each of the orifices 209a has anupper orifice portion opening toward the first fluid chamber 207 and alower orifice portion extending downwardly coaxially from the upperorifice portion and opening toward the second fluid chamber 208. Thepartition 206a has a storage chamber 200 defined therein across theorifices 209a and held in communication with the fluid chambers 207, 208through the orifices 209a. The movable plate 210a which is movable atleast axially of the orifices 209a dependent on the difference betweenthe fluid pressures in the fluid chambers 207, 208 is disposed in thestorage chamber 200. The movable plate 210a serves as a flow regulatingmeans. As described above, the upper orifice portion of each of theorifices 209a includes a tapered or flaring portion flaring toward themovable plate 210a.

The effective length L of the orifices 209a and their inlet area(cross-sectional) area of the smaller-diameter portion thereof) Sw aregiven by the following equation: ##EQU8## Where

k is the product of the static spring constant of the elastomeric member204a and the dynamic magnification thereof at a resonant frequency,

S'E is the amount of change in the volume of the first fluid chamber 207per unit relative displacement between the joint member 201a and thesupport member 202a.

f1 is the resonant frequency of the elastomeric member 204, and

ρ is the density of the filled fluid.

The appropriate relationship between L and Sw can be determined byputting the measured values of k, f1, S'E, and ρ into the aboveequation. By thus setting L and Sw to optimized values, the resonance ofthe elastomeric member 204a can be suppressed through the resonantaction of the fluid in the orifices 209a.

If the orifices 209a for suppressing the resonance of the elastomericmember 204a, i.e., antiresonant orifices, are designed for a smallerdiameter or a larger effective length to shift the resonant frequency ofthe fluid in the orifices 209a toward a lower frequency then the dynamicspring constant becomes higher in a high frequency range, but becomeslower in a secondary vibration range (40-200 Hz) (see FIG. 23).Conversely, if the frequency of the fluid in the orifices 209a isshifted toward a higher frequency, then the dynamic spring constantbecomes higher in a high frequency range, but becomes lower in asecondary vibration range (see FIG. 24). This effect is utilized whenthe dynamic spring constant is to be lowered at a certain frequency.

In the fluid-filled vibroisolating device shown in FIG. 9, each of theorifices 209a flares from the first fluid chamber 207 toward the movableplate 210a. Therefore, the pressure-bearing area of the movable plate210a is large and the area of contact between the movable plate 210a andthe partition 206a which holds the movable plate 210a is small.Consequently, when vibration with a small amplitude at medium and highfrequencies is applied, the movable plate 210a is smoothly moved, thuspreventing the dynamic spring characteristics from being lowered.

FIG. 25 shows, by way of comparison, a fluid-filled vibroisolatingdevice having a single antiresonant orifice 209. When vibration isapplied, the fluid between the movable plate 210 and the orifice 209makes complex motions as indicated by the arrows, and hence such fluidmotions are slightly dampened, with the result that the dynamic springcharacteristics is lowered in the second vibration range. In order toobtain good dynamic spring characteristics, therefore, the antiresonantorifice should preferably be composed of a combination of orifices.

FIG. 10 shows a fluid-filled vibroisolating device according to a firstmodification of the second embodiment shown in FIG. 9. Each of orifices209b in a partition 206b has flaring portions 212a, 212b flaring towarda movable plate 210b;

FIG. 11 illustrates a fluid-filled vibroisolating device according to asecond modification having a low-frequency orifice 213 defined centrallythrough the partition and having upper and lower openings opening intothe fluid chambers 207, 208, respectively. The orifice 213 serves as aflow regulating means or low-frequency damping means for improvingdamping characteristics at low frequencies below 20 Hz, for example.

FIG. 12 shows a fluid-filled vibroisolating device according to a thirdmodification. The fluid-filled vibroisolating device has a low-frequencyorifice 214 defined centrally in a partition 206c and extending from aflaring portion of an orifice near the elastomeric member toward a fluidchamber near the diaphragm. The fluid-filled vibroisolating devicetherefore has high damping characteristics with respect to low-frequencyvibration applied with a large amplitude.

FIG. 13 shows a fluid-filled vibroisolating device according to a fourthmodification. The fluid-filled vibroisolating device has low-frequencyorifices 215 defined in a movable plate 210b at positions in selectedones of the orifices 209a in the partition 206a. The fluid-filledvibroisolating device also has high damping characteristics with respectto low-frequency vibration applied with a large amplitude.

A fluid-filled vibroisolating device according to a fifth modificationshown in FIG. 14 is similar to the fluid-filled vibroisolating deviceshown in FIG. 10, but differs therefrom in that a low-frequency orifice216 is defined centrally through a partition 206d. The fluid-filledvibroisolating device also has high damping characteristics with respectto low-frequency vibration applied with a large amplitude.

FIG. 15 shows a fluid-filled vibroisolating device according to a sixthmodification. A partition 206e has a low-frequency orifice 218 definedtherein and including an opening 217 connected to the flaring portion ofan orifice 209c near the outer periphery of the partition 206e and theelastomeric member 204a, and extending through the outer periphery ofthe partition 206e to an opening 219 which opens to the fluid chamber208 near the diaphragm 205. The fluid-filled vibroisolating deviceprovides very high damping capability in a low frequency range.

FIG. 16 shows a fluid-filled vibroisolating device in accordance with aseventh modification. A partition 206e has a low-frequency orifice 220defined in the outer periphery thereof and including an opening 221 bearthe elastomeric member 204a, and extending through the outer peripheryof the partition 206e to an opening 222 which opens to the fluid chamber208 near the diaphragm 205. The fluid-filled vibroisolating device alsoprovides very high damping capability in a low frequency range.

According to an eighth modification shown in FIG. 17, a flexible movableplate 223 is held in a partition 206f in a loose condition, and thepartition 206f has a low-frequency orifice 224 defined centrally throughthe partition 206f.

FIG. 18 is illustrative of a fluid-filled vibroisolating deviceaccording to a ninth modification. In this modification, a pair oflow-frequency orifices 225, 226 is defined centrally through a partition206g, and oppositely directed check valves 227, 228 are associatedrespectively with the orifices 225, 226. By suitably adjusting therigidity of the check valves 227, 228, the fluid-filled vibroisolatingdevice can provide good damping characteristics in a wide frequencyrange.

FIG. 19 illustrates a fluid-filled vibroisolating device according to atenth modification. A partition 229 has a low-frequency orifice 229defined therethrough, and a control valve 230 is supported on thepartition 229 for movement into and out of the orifice 229 to adjust thecross-sectional area of the fluid flow passage through the orifice 229.When a large dynamic input load is applied to the fluid-filledvibroisolating device, suitable damping characteristics can be providedby operating the control valve 230.

FIG. 20 shows a fluid-filled vibroisolating device according to aneleventh modification which has a second fluid chamber which isidentical to the first fluid chamber described above in the previousmodifications. Confronting joint members 201b, 201c are interconnectedby a link member 231, and also coupled to a support member 202b byrespective elastomeric members 204b, 204c. A partition 206i has alow-frequency orifice 232 defined centrally therethrough. With thisconstruction, even when a large tensile input load is applied, since thefluid pressure in one of the fluid chambers is positive, the fluidchamber is prevented from developing cavitation. Thus, good dampingcharacteristics can be obtained with respect to large loads.

FIG. 21 shows a fluid-filled vibroisolating device according to atwelfth modification. In this modification, a pair of joint members201d, 201e is interconnected with a partition 233 sandwichedtherebetween. Annular elastomeric members 204e, 204f are interposedbetween the joint members 201d, 201e, the partitions 233 and a supportmember 202c. The partition 233 has a plurality of orifices 209d, 209e inwhich there are loosely fitted movable plates 234, 235 lying across theorifices 209d, 209e, the movable plates 234, 235 having respectivelow-frequency orifices 236, 237. The orifices 209d, 209e have respectiveflaring portions 238, 239 flaring from the ends near the elastomericmember 204d toward the movable plates 234, 235.

FIG. 22 shows a fluid-filled vibroisolating device according to athirteenth modification which differs from the twelfth modification inthat the elastomeric member 204d of FIG. 21 is replaced with a diaphragm240.

With the second embodiment and its first through thirteenthmodifications, as described above, the elastomeric member interposedbetween the joint member and the support member constitute at least partof the chamber wall of a corresponding one of the first and second fluidchambers disposed adjacent to each other with the partition therebetweenand filled with the noncompressible fluid. By appropriately selectingthe effective length and the inlet area of the orifices, the elastomericmember is prevented from resonating through the resonant action of thefluid in the orifices. The flaring shape of the orifices allows themovable plate to move smoothly for thereby lowering the dynamic springconstant when vibration with a small amplitude at a high frequency isapplied. The fluid-filled vibroisolating device is simple in structureand compact since only the movable plate is added and the orifices areshaped to flaring contour.

Fluid-filled vibroisolating devices according to a third embodiment anda modification thereof will be described with reference to FIGS. 26through 29.

FIG. 26 shows in vertical cross section a fluid-filled vibroisolatingdevice in accordance with a third embodiment of the present invention,the fluid-filled vibroisolating device being used as an engine mount.

As shown in FIG. 26, the fluid-filled vibroisolating device, generallydenoted at 103, comprises a conical cylindrical elastomeric member 302of rubber having a large wall thickness and a housing 303 made of arigid material such as steel sheet. The elastomeric member 302 may havean intermediate reinforcing member 302a of the first and secondembodiments. The housing 303 comprises a substantially cylindrical upperhousing 303a and a substantially cylindrical lower housing 303b. Thelower housing 303b has a flange 303c to be attached to a support bodysuch as a vehicle frame. In the third embodiment, therefore, the housing303 serves as a support member.

The outer peripheral surface of the lower end of the elastomeric member302 is bonded to the inner peripheral surface of the upper end of theupper housing 303a upon vulcanization of the elastomeric member 302. Anattachment member or joint member 305 having a bolt 304 for being fixedto a vibrating body or an engine is bonded to the upper end of theelastomeric member 302 upon vulcanization of the elastomeric member 302.The engine is thus supported on the vehicle frame through theelastomeric member 302, which is elastically deformed dependent onvibration of the engine.

A partition 306 is disposed below the elastomeric member 302 in coveringrelation to the lower opening of the elastomeric member 302. A diaphragm207 of rubber having an easily deformable thin portion is locatedunderneath the partition 306. The partition 306 and the diaphragm 307has on their peripheries attachment flanges 306a, 307a clamped betweenthe lower end of the upper housing 303a and the upper end of the lowerhousing 303b. The partition 306 and the diaphragm 307 are fixed to thehousing 303 by deforming the lower end of the upper housing 303a overthe upper end of the lower housing 303b thereby providing a fluidtightseal between and upper and lower housings 303a, 303b.

The engine mount 301 defines therein a fluidtight space or chambersurrounded by the elastomeric member 302 and the diaphragm 307 anddivided into upper and lower or expandable/contractable main andauxiliary fluid chambers 308, 309 by the partition 306. The fluidtightspace is filled with a noncompressible fluid such as oil, water, or thelike.

The main fluid chamber 308 above the partition 306 is surrounded by theelastomeric member 302 and variable in its volume by elastic deformationof the elastomeric member 302 due to vibration cf the engine. Theauxiliary fluid chamber 309 below the partition 306 is surrounded by thediaphragm 307 which is easily elastically deformable. The area beneaththe lower surface of the diaphragm 207 is vented to atmosphere.Therefore, the volume of the auxiliary fluid chamber 309 is freelyvariable by deformation of the diaphragm 307 dependent on the fluidpressure in the auxiliary fluid chamber 309.

As illustrated in FIGS. 27 and 28, the partition 306 is in the form of arelatively thick disc having an attachment flange 306a on its periphery.The partition 306 comprises an upper plate 312 including a base plate310 in the form of a thin steel sheet with a layer 311 of rubber bondedthereto upon vulcanization, and a lower plate 313 in the form of a thinsteel sheet.

The base plate 310 of the upper plate 312 is of hat shape having aflange on its peripheral edge and a number of circular openings 314defined in its central area. The base plate 310 also has a rectangularopening 315 defined in one side of its top. The rubber layer 311 isfilled in the recess of the base plate 310 and joined to the centrallower surface of base plate 310. The rubber layer 311 has a number oforifices 316 connected respectively to the openings 314 of the baseplate 310. The orifices 316 have tapered portions flaring away from thebase plate 310 toward the lower end thereof. The openings 314 of thebase plate 310 and the orifices 316 of the rubber layer 311 jointlyprovide relatively long upper orifices 317 extending vertically throughthe upper plate 312.

The rubber layer 311 has an arcuate groove 318 defined in its lowersurface around its periphery, and a circular cavity 319 defined in itslower central surface. The groove 318 has an end communicating with therectangular opening 315 defined in the base plate 310. The cavity 319 isof a size large enough to cover the area where the orifices 316 aredefined. The rubber layer 311 has a portion projecting upwardly on theouter peripheral surface of the base plate 310 through an opening 320defined in the peripheral portion of the top of the base plate 310. Theprojecting portion of the rubber layer 311 serves as a stopper 321 forpreventing the elastomeric member 302 from being excessively deformed.

The lower plate 313 has tapered projecting portions aligned with theupper orifices 317 of the upper plate 317, i.e., the openings 314 of thebase plate 310 and the orifices 316 of the rubber layer 311, and havingtheir diameter progressively smaller downwardly. These taperedprojections have respective lower orifices 322 opening downwardly. Thelower orifices 322 have a relatively large diameter. The lower plate 313has a rectangular opening 323 defined in one side thereof and held inregistry with the other end of the arcuate groove 318 defined in theouter periphery of the lower surface of the rubber layer 311.

The partition 306 is constructed of the lower plate 313 and the upperplate 312 which is placed over the lower plate 313, the lower and upperplates 313, 312 having outer peripheral edges welded to each other. Theupper orifices 317 of the upper plate 312 and the lower orifices 322 ofthe lower plate 313 jointly provide orifices which are effective indamping vibration in medium and high frequencies. The rectangularopening 315 of the base plate 310 of the upper plate 312, the groove 318of the rubber layer 311, and the rectangular opening 323 of the lowerplate 313 jointly provide an orifice providing fluid communicationbetween the main and auxiliary fluid chambers 308, 309 and serving as ameans for damping vibration in low frequencies.

Between the upper and lower plates 312, 313, the cavity 319 defined inthe lower surface of the rubber layer 311 provides a thin disc-shapedspace in which a movable or vibratable plate 325 in the form of a thindisc is housed. The vibratable plate 325 has a thickness smaller thanthe thickness of the disc-shaped space, i.e,. the depth of the cavity319. Therefore, the vibratable plate 325 is vertically movable betweenthe lower surface of the upper plate 312 and the upper surface of thelower plate 313. The fluid pressure in the main fluid chamber 308 actson the upper surface of the vibratable plate 325 through the upperorifices 317, and the fluid pressure in the auxiliary fluid chamber 309acts on the lower surface of the vibratable plate 325 through the lowerorifices 322.

Operation of the engine mount thus constructed will be described below.

When the engine rotates in medium and high speed ranges as while themotor vehicle is running normally, vibration with a small amplitude atmedium and high frequencies is applied to the engine mount 301.Therefore, the elastomeric member 301 is elastically deformed to a smalldegree. As a result, the volume of the main fluid chamber 308 is variedto vary the fluid pressure therein. The change in the fluid pressure istransmitted through the upper orifices 317 of the partition 306 to thespace between the upper and lower plates 312, 313. The vibratable plate325 in that space is vertically vibrated dependent on the transmittedchange in the fluid pressure, thereby taking up the change in the volumeof the main fluid chamber 308. As the vibratable plate 323 is thusvibrated, the fluid flows through the lower orifices 322 to vary thefluid pressure in the auxiliary fluid chamber 309. The change in thefluid pressure in the auxiliary fluid chamber 309 is taken up by thechange in the volume of the auxiliary fluid chamber 309 which is causedby deformation of the diaphragm 307.

The elastic deformation of the elastomeric member 302 is allowed withoutany substantial resistance by the vibration of the vibratable plate 325,so that the vibration applied at the time can be absorbed by theelasticity of the elastomeric member 302. When the elastomeric member302 resonates with the engine vibration, the fluid flowing through theupper orifices 317 also resonates with the vibration at a certain phasedifference, with the result that the resonant vibration of theelastomeric member 302 is suppressed.

When vibration with a very large amplitude is applied as while theengine is being cranked or violently shaked during normal travel of thevehicle, the elastomeric member 302 is largely deformed to largely varythe volume of the main fluid chamber 308. In this case, the change inthe volume of the main fluid chamber 308 cannot be absorbed even by thevertical movement of the vibratable plate 325. The fluid is forced toflow through the slender and long low-frequency orifice 324 whichpresents resistance to the flow of the fluid for dampen the appliedvibration.

In order for the fluid flowing through the orifices 317 to resonate at acertain frequency, it is necessary that the effective cross-sectionalshape of the orifices 317 be exactly established and their length besufficiently long. Moreover, in order to allow the elastomeric member302 to be elastically deformed without being subjected to resistance inmedium and high frequency ranges, the total cross-sectional area of theupper and lower orifices 317, 322 serving as the medium- andhigh-frequency orifices should be sufficiently large to reduceresistance to the fluid flowing through these orifices. Therefore, ifthe orifices 317, 322 should be small in diameter, the number of theseorifices should be increased. So that the fluid flowing between theorifices 317, 322 and the space holding the vibratable plate 325 thereinwill not produce swirls, the orifices 317, 322 should be of a taperedshape.

The low-frequency orifice 324 should be small in cross-sectional areaand very long so that the fluid flowing therethrough will sufficientlybe dampened.

The upper plate 312 with the upper orifices 317 and the low-frequencyorifice 324 defined therein is constructed of the base plate 310 in theform of a thin steel sheet and the rubber layer 311 bonded thereto.Therefore, the effective cross-sectional shapes of the orifices 317, 324can accurately be determined by the openings 314, 315 defined in thebase plate 310. Since the longitudinal shapes of the orifices 317, 324are defined by the rubber layer 311 which can easily be formed, theorifices 317, 324 can easily be shaped to complex configurations such astapered contours. Because the portions between the upper orifices 317and the portions between the orifices 317, 324 may be made thin, thenumber of medium- and high-frequency orifices may be increased toincrease the total cross-sectional area thereof.

The rigidity of the partition 306 is maintained by the base plate 310and the lower plate 313 which are of steel sheets. Since the thicknessof the partition 306 is given by the rubber layer 311, the partition 306may be lightweight but have the long orifices 317, 324.

The upper plate 312 with the rubber layer 311 bonded to the steel baseplate 310 makes it possible to provide the rubber stopper 321 on theouter periphery of the upper surface thereof. When vibration with alarge amplitude is applied, the inner surface of the elastomeric member302 engages the stopper 321 to prevent the elastomeric member 302 frombeing excessively deformed, and hence the attachment member 305 isprevented from hitting and damaging the partition 306. Since the rubberlayer 311 provides a seal between the upper and lower plates 312, 313,no other seal member is required therebetween. The seal member providinga seal between the upper plate 312 and the housing 303 may be integrallyformed with the upper plate 312 by the rubber layer 311. Accordingly,the number of parts of the fluid-filled vibroisolating device isreduced.

FIG. 29 shows a partition 306 according to a modification for use in theengine mount 301 shown in FIG. 26. Those parts in FIG. 29 whichcorrespond to those of the partition 306 shown in FIGS. 27 and 28 aredenoted by corresponding reference numerals.

The partition 306 of FIG. 29 includes the same upper plate 312 as thatof FIGS. 27 and 28, and a lower plate 313 comprising a base plate 330 inthe form of a thin steel sheet and a rubber layer 331 bonded theretoupon vulcanization.

More specifically, the base plate 330 is in the form of a thin dishhaving a flange on its outer peripheral edge and has a number ofcircular openings 334 defined in a central bottom thereof. The baseplate 330 also has a rectangular opening 335 defined in one side of itsbottom and coupled to the other end of the groove 318 defined in theouter periphery of the lower surface of the upper plate 312. The rubberlayer 331 is filled in the cavity of the base plate 330 and has a numberof orifices 336 held in registry with the respective openings 334 of thebase plate 330. The orifices 336 have upper ends opening at the uppersurface of the rubber layer 331 and having tapered portions flaringupwardly. The openings 334 of the base plate 330 and the orifices 336 ofthe rubber layer 331 jointly provide lower orifices extending verticallythrough the lower plate 313.

The other structural details of the partition 306 shown in FIG. 29 arethe same as those of the partition 306 shown in FIGS. 27 and 28.

With a fluid-filled engine mount 301 incorporating the partition 306shown in FIG. 29, the lower orifices 322 of the lower plate 313 haveaccurate cross-sectional shapes and sufficient lengths so that the fluidflowing through the lower orifices can develop resonance. Therefore, thefluid is caused to resonate in the entire medium- and high-frequencyorifices comprising the upper and lower orifices 317, 322, with theconsequence that the resonance of the elastomeric member 302 canreliably be suppressed.

The space in which the vibratable plate 325 is housed and vibratable hasits entire peripheral edge defined by the rubber layers 311, 331. As aconsequence, when the vibratable plate 325 is vibrated, the vibratableplate 325 is brought into contact with the rubber layers 311, 331, andhence large hitting sounds or noise is reliably prevented from beingproduced.

In the third embodiment, the vibratable plate 325 is held in thepartition 306. The present invention is however not limited to suchconstruction, but may also be applied to an engine mount which absorbsapplied vibration only with orifices. In such an alternative, the lowerplate 313 may be dispensed with.

The mount of the third embodiment is not limited to an automotive enginemount, but may be used as any of various fluid-filled vibroisolatingdevices such as a suspension mount.

With the fluid-filled vibroisolating device of the third embodiment, asdescribed above, the partition disposed between the main and auxiliaryfluid chambers and having orifices providing fluid communication betweenthe main and auxiliary fluid chambers comprises the base plate in theform of a thin metallic sheet and the rubber layer bonded thereto. Sincethe thickness of the partition is maintained by the rubber layer, thepartition may be lightweight but still thick. Consequently, the orificesdefined in the partition may sufficiently be long. Since the rubber caneasily be formed to desired shape, orifices of complex shape may bedefined in the partition. Moreover, burrs can easily be removed from thepartition and the attachment surface of the partition for attachment tothe support member or the like is not required to be machined.Therefore, the number of processing steps required after the partitionhas been fabricated is reduced, and the cost of manufacture is lowered.

Inasmuch as the rubber stopper and seal member can integrally be formedwith the partition, the number of parts of the partition is alsoreduced. Where the vibratable plate is disposed in the partition, sincethe partition is held by the rubber layer or layers, any strong hittingsounds or noise which would otherwise be produced by the vibration ofthe vibratable plate can effectively be eliminated.

The fluid-filled vibroisolating device can be designed with greaterfreedom and has good vibration absorbing or damping characteristics.

The partition 306 of the third embodiment may be incorporated in thefluid-filled vibroisolating devices of the first and second embodiment.

Although there have been described what are at present considered to bethe preferred embodiments of the present invention, it will beunderstood that the invention may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The present embodiments are therefore to be considered in all aspects asillustrative, and not restrictive. The scope of the invention isindicated by the appended claims rather than by the foregoingdescription.

We claim:
 1. A fluid-filled vibroisolating device comprising:a jointmember adapted to be joined to a vibrating body; a support memberadapted to be supported on a supporting body and defining an expandableand contractable auxiliary fluid chamber filled with a fluid; Anelastomeric member interconnecting said joint and support members anddisposed in a vibrating, direction in which the vibrating body vibrates,said elastomeric member, said joint member, and said support memberjointly defining an expandable and contractable main fluid chamberfilled with fluid. a partition mounted in said support member andseparation said main and auxiliary fluid chambers from each other; saidpartition having a storage chamber defined therein and held incommunication with said main and auxiliary fluid chambers through aplurality of first orifices opening into said main fluid chamber and aplurality of second orifices opening into said auxiliary fluid chamberin coaxial relation to the first orifices as pairs; and flow regulatingmeans comprising a movable plate movably disposed in said storagechamber and movable at least axially of said first and second orificesdependent on the difference between fluid pressures in said main andauxiliary fluid chambers, said first and second orifices having openingsopening toward said movable plate, said openings of at least one of saidfirst and second orifices having tapered portions flaring toward saidmovable plate.
 2. A fluid-filled vibroisolating device according toclaim 1, wherein said flow regulating means further compriseslow-frequency damping means having first and second openings openinginto said main and auxiliary fluid chambers to provide fluidcommunication between said main and auxiliary fluid chambers.
 3. Afluid-filled vibroisolating device according to claim 2, wherein saidfirst opening of said low-frequency dampling means opens into one ofsaid first orifices.
 4. A fluid-filled vibroisolating device accordingto claim 2, wherein said low-frequency damping means is defined in saidmovable plate and opens into at least a pair of orifices of said firstand second orifices in pairs.
 5. A fluid-filled vibroisolating deviceaccording to claim 4, further comprising a second joint member and asecond elastomeric member which are substantially identical to saidjoint member, and said elastomeric member for defining said main fluidchamber therein, wherein said auxiliary fluid chamber being partiallydefined by said second joint member and said second elastomeric member,wherein said joint members being disposed in confronting relation toeach other and said partition being partially sandwiched by said twojoint members.
 6. A fluid-filled vibroisolating device according toclaim 5, further comprising an annular elastomeric member interposedbetween said support member and said partition.
 7. A fluid-filledvibroisolating device according to claim 2, wherein said low-frequencydamping means comprises a passage defined in said partition along anouter periphery thereof.
 8. A fluid-filled vibroisolating deviceaccording to claim 7, wherein said first opening of said low-frequencydamping means opens into at least one of said first orifices.
 9. Afluid-filled vibroisolating device according to claim 2, wherein saidlow-frequency damping means comprises a pair of passages definedcentrally in said partition and providing fluid communication betweensaid main and auxiliary fluid chambers, said passages being associatedwith oppositely directed check valves, respectively.
 10. A fluid-filledvibroisolating device according to claim 2, wherein said low-frequencydamping means comprises a passage defined in said partition andproviding fluid communication between said main and auxiliary fluidchambers, said passage having said first and second openings openinginto said main and auxiliary fluid chambers, respectively, and a controlvalve disposed in said passage for regulating the cross-sectional areaof said passage.
 11. A fluid-filled vibroisolating device according toclaim 2, wherein said movable plate of said flow regulating meanscomprises a flexible member held in said storage chamber in a loosecondition.
 12. A fluid-filled vibroisolating device according to claim2, further including a second joint member and a second elastomericmember which are substantially identical to the joint member and theelastomeric member which define said main fluid chamber therein, saidauxiliary fluid chamber being defined by said second joint member andsaid second elastomeric member, said joint members being disposed inconfronting relation to each other, and interconnected by a link.
 13. Afluid-filled vibroisolating device according to claim 1, wherein saidelastomeric member includes a reinforcing member integrally formedtherewith for preventing the elastomeric member from being collapsed.14. A fluid-filled vibroisolating device according to claim 1, whereinsaid partition comprises an upper plate comprising a base plate in theform of a thin metallic sheet and an elastomeric body bonded thereto,and a lower plate comprising a thin metallic sheet.
 15. A fluid-filledvibroisolating device according to claim 14, wherein said upper platehas said first orifices and said storage chamber defined therein, andsaid lower plate has said second orifices defined therein.
 16. Afluid-filled vibroisolating device according to claim 14, wherein saidupper plate has a stopper comprising a portion of said elastomeric bodywhich projects through at least one opening defined in said base plate,for preventing said elastomeric member from being excessively deformed.17. A fluid-filled vibroisolating device according to claim 14, whereinsaid lower plate comprises a base plate in the form of a thin metallicsheet and an elastomeric body bonded thereto.